Electric and hybrid vehicles have become more common due to the availability of traction batteries with high energy density, for example using lithium-ion technology. Such batteries are also generally characterized by relatively low weight, but relatively high operating voltage. In a hybrid vehicle the traction battery may be used to assist an internal combustion engine in order to boost acceleration.
A traction battery of a vehicle is generally confined within a casing, but necessarily connections through the casing are required, for example for electric cables. Such cables may convey traction current, charging current, or control signals. Electric cables generally consist of a conductor (e.g. copper) surrounded by an insulating material of plastic or the like, and are required to be flexible.
The potential high energy density of a traction battery generally requires careful monitoring and management in order to ensure safe reliable operation thereof. However in the event of catastrophic damage, for example in a vehicle collision, there is a possibility that control systems may become damaged, or that the safety of the traction battery may be otherwise compromised. Generally speaking, failure is characterized by an increase in battery temperature above the normal maximum of about 50-70° C.
In the event of catastrophic damage of a traction battery, the internal temperature thereof may rise substantially, and exceed the melting temperature of a cable insulator. The loss of insulator may allow the battery casing to be breached, subjecting vehicle components around the battery casing to this high temperature, and in turn causing further potential damage to the vehicle. In particular a connector at the wall of the battery casing may be exposed to high temperatures and, if damaged may provide a significant breach of the battery casing.
What is required is a means of inhibiting a breach of the battery casing due to softening or melting of the insulation of an electrical cable of the battery, or of the materials of an electrical connector at the casing boundary.